Wear is one of the main forms of material damage, which may cause surprisingly large economic loss. A great number of equipments used in industries such as metallurgical mine, agricultural machinery and coal industry, fail mostly because of material wear. According to statistics, in industrialized countries, economic loss caused by wear of mechanic equipments and components accounts for about 4% of the gross national production, wherein abrasive wear accounts for 50% of total metal wear. In China, steel consumed by material wear per year is up to above one million tons, in which 60-80 thousand tons of steel plates are consumed per year only in middle grooves of scrape plate conveyor in coal mining.
As an important type of steel, the high-strength low-alloy wear-resistant steel, is applied widely to fields like mining machinery, engineering machinery, agricultural machinery and railway transportation. With the rapid development of China industry, various mechanic equipments become more complicated, larger and lighter, which requires this type of steel used for making these equipments, not only to be of higher hardness and strength, but also good toughness and forming performance. In recent decades, the research and application of high-strength wear-resistant steel develops very fast. This type of steel is developed on basis of high-strength low-alloy weldable steel, with good wear resistance and the service life thereof being many times longer than that of traditional structural steel plate; the manufacturing process thereof is simple, which normally includes quenching and tempering directly after rolling, or controlled rolling and controlled cooling to strengthen.
Now, in the field of high-strength wear-resistant steel, there have been many related patents and patent applications in China and other countries. With regard to ultrahigh-strength low-carbon (0.205-0.25%) wear-resistant steel, it is necessary to add Nb, V or B in patents JP1255622A, JP2002020837A, CN101469390, CN101186960A and CN101775545A, and many expensive alloy elements in patents JP2002020837A, JP2002194499A, CN1208776A, CN101469390A, CN101186960A and CN101775545A. As to the processes, in most of these patents, quenching (DQ or offline heating and quenching)+offline tempering is adopted, whereby the low-temperature impact value at −40° C. of the finished steel plate is not high, that is, mainly between 17-50 J, which cannot meet the demand of users.
Hardox400 wear-resistant steel plate (4-32 mm) (C≦0.18, Si≦0.70, Mn≦1.6, P≦0.025, S≦0.010, Ni≦0.25, Cr≦1.0, Mo≦0.25, B≦0.004) produced by Sweden SSAB, contains low content of expensive alloy elements, with the hardness of between HBW370-430, and good wear resistance. The steel plate of 20 mm thick has typically a yield strength of 1000 MPa, A50 of 16%, and longitudinal Akv at −40° C. of 45J. Although its hardness, strength and wear resistance is high, both the standard and physical impact values thereof are not high, and it has no TRIP (self hardening) effect in use.
Currently, it is necessary to provide a high-strength wear-resistant medium steel plate with TRIP effect.